Microstructure, Tensile Properties, and Fracture Toughness of an In Situ Rolling Hybrid with Wire Arc Additive Manufacturing AerMet100 Steel

Abstract

As a type of ultra-high strength steel, AerMet100 steel is used in the aerospace and military industries. Due to the fact that AerMet100 steel is difficult to machine, people have been exploring the process of additive manufacturing to fabricate AerMet100 steel. In this study, AerMet100 steel was produced using an in situ rolling hybrid with wire arc additive manufacturing. Microstructure, tensile properties, and fracture toughness of as-deposited and heat-treated AerMet100 steel were evaluated in different directions. The results reveal that the manufacturing process leads to grain fragmentation and obvious microstructural refinement of the AerMet100 steel, and weakens the anisotropy of the mechanical properties. After heat treatment, the microstructure of the AerMet100 steel is mainly composed of lath martensite and reversed austenite. Alloy carbides are precipitated within the martensitic matrix, and a high density of dislocations is the primary strengthening mechanism. The existence of film-like austenite among the martensite matrix enhances the toughness of AerMet100 steel, which coordinates stress distribution and restrains crack propagation, resulting in an excellent balance between strength and toughness. The AerMet100 steel with in situ rolling is isotropy and achieves the following values: an average ultimate strength of 1747.7 ± 16.3 MPa, yield strength of 1615 ± 40.6 MPa, elongation of 8.3 ± 0.2% in deposition direction, and corresponding values in the building direction are 1821.3 ± 22.1 MPa, 1624 ± 84.5 MPa, and 7.6 ± 1.7%, and the KIC value up to 70.6 MPa/m0.5.

Editorial for the Special Issue on Laser Additive Manufacturing: Design, Materials, Processes, and Applications, 2nd Edition

“…This Special Issue covers a wide range of forming materials, including zirconium alloys [ 24 ], titanium alloys [ 20 , 23 ], steel [ 21 , 25 , 26 ], composites (e.g., electroless copper and carbon fiber [ 27 ]), and in particular, metallic multi-materials (e.g., copper/silver [ 22 ]), 4D printing materials (e.g., NiTi, smart materials for soft interactive hydrogel [ 19 ]).…”

“…Lei et al [ 21 ] reported that AerMet100 steel was produced using an in situ rolling hybrid with wire arc additive manufacturing. In their work, the microstructure, tensile properties, and fracture toughness of as-deposited and heat-treated AerMet100 steel were evaluated in different directions.…”

“…This Special Issue focuses on macro-advanced manufacturing (e.g., laser powder bed fusion (L-PBF) [ 18 ], wire arc additive manufacturing (WAAM) [ 21 ]), but also on micro-advanced manufacturing (e.g., laser photochemical synthesis [ 19 ]). Furthermore, the process optimizations on the adhesion strength [ 28 ] and the mechanical properties [ 24 ] (in-process) and the influence of aging treatment regimens on the microstructure and mechanical properties [ 25 ] (post-process) were investigated.…”

“…As depicted in Figure 1 , this Special Issue featured a diverse array of topics, publishing a total of 11 contributions, comprising 10 original research articles and 1 review paper. After the high-quality reviewing process, four articles [ 18 , 19 , 20 , 21 ] were selected as Editor’s Choice. Each of them is briefly introduced below according to four aspects (i.e., design, materials, processes, and applications) of the laser additive manufacturing in this Special Issue.…”